Add ChangeLog entry for HKDF
diff --git a/ChangeLog b/ChangeLog
index 348864c..1e5d73d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -54,6 +54,10 @@
This function is necessary to determine when it is safe to idle on the
underlying transport in case event-driven IO is used.
+Features
+ * Implement the HMAC-based extract-and-expand key derivation function
+ (HKDF) per RFC 5869. Contributed by Thomas Fossati.
+
Bugfix
* Fix a spurious uninitialized variable warning in cmac.c. Fix independently
contributed by Brian J Murray and David Brown.